The present invention relates to a bumper skin made of plastics material.
Bumper skins are known that include orifices for receiving light units, such as fog lights, that are located between their front portions and their overriders.
Such skins are often made by injection molding, a manufacturing technique that is nowadays well mastered and that produces parts of shapes and dimensions that are well controlled.
The orifices provided in such parts may be obtained directly by molding or they may be obtained by punching, during a reworking operation. However even when reworking, with very few exceptions, the orifice is to be found within a shape arrangement, thereby creating a shape irregularity in the visible face of the skin.
Thus, because of the orifice itself or because of the arrangement that contains it, a shape irregularity appears in the visible face of the bumper skin, between its front portion and each of its side overriders.
For parts that are painted, such irregularities present no difficulty.
In contrast, for mass colored parts, it is observed that the plastics material has its progress within the mold cavity braked by the outlines of the irregularity and splits into at least two fronts of material that become separate on going past the irregularity. These fronts of material meet again downstream from the irregularity within the overriders, where the fronts weld together along a line of welding, also known as “knitting”, thereby leaving visible faces on the overriders.
As a result, unless multiple complex and expensive proportions are taken, it is not possible to obtain a bumper skin that presents a shape irregularity between its front portion and its overriders, merely by the simple technique of injection molding a plastics material and without subsequent painting.